1. Field of the Invention
The present invention relates to a deflection scanner for, for example, a laser beam printer using a rotator held with a ball bearing.
2. Related Background Art
A precise ball bearing has been employed for a rotator that rotates at a high speed or with high precision and is designed, especially, for a laser beam printer.
FIG. 1 shows an example of prior art of a deflection scanner for use in a laser beam printer. A flange 2 is pressed into a rotating shaft 1. A rotary polygon mirror 3 is placed on the flange 2. A yoke 4 is fixed under the flange 2. A drive magnet 5 is fixed on the inner surface of the yoke 4 and opposed to a stator coil 6. The drive magnet 5 and stator coil 6 form a drive motor to rotate the rotary polygon mirror 3 via the rotating shaft. The rotating shaft 1 is fitted into an inner ring of a ball bearing 8 pressed into a housing 7. The housing 7 is fixed in an optical case 10 with screws 9.
In the foregoing example of prior art, the screws 9 are used to fix the housing 7 in the optical case 10. The screws 9 are arranged outside so as not to interfere with the rotating yoke 4. Therefore, the housing 7 becomes large in size. This may result in a heavy or high-cost scanner. Moreover, four to five screws 9 are employed, increasing the number of parts , man-hours, and cost.